It's a Japanese Arisaka. The chrysanthemum symbols have been ground off the bolt as well as the receiver, so it probably didn't come home in some GI's duffle. It looks like you have a type 42 bayonet with it as well.
It looks like a type 99, but the photo's proportions seem a little off from a type 99. Can you measure the barrel itself and post that length? It could just be my eye and the pictures. Also if we had a close up picture of the rear sight it would probably help. Some of the type 99's had an odd looking anti-aircraft sight back there, but about mid WWII they stopped putting it on them.

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